My friend has a 2001mbox, tune only, s4. He has complained about erratic performance. There are no boost leaks or misfires, the requested vs actual boost is good. The only thing I can see is that it's pulling fuel on long and short term, I know ltft is -12+%. And pulling timing on bank 2, cfs are 12-15+ degrees(arc seconds I assume). Bank 1 is under 5(usually, and I think only goes that high from bank2 acting up.

O2 sensors sweep good, but I don't have a wideband to compare their accuracy against. My initial thoughts are bad O2s or poor injector spray.
Looking for some alternatives to look into. Neither of us have too much time to diagnose these days.